Forty days in Jiangyan

(1) The weather condition of the day is: cloudy weather turns to sleet weather.

(2) The wind direction is northeast wind.

(3) The lowest temperature is -7℃, the highest temperature is 2℃, and the daily temperature difference is 9℃.

(4) The temperature of -7℃ appeared around sunrise that day.

So the answer is:

(1) cloudy; Sleet;

(2) Northeast China;

(3)-7; 9;

(4) sunrise.